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United States Patent |
5,706,380
|
Le Noane
,   et al.
|
January 6, 1998
|
Apparatus and a method for identifying and splicing multicore fibers
Abstract
The invention relates to apparatus for identifying and splicing at least
one multicore optical fiber and including both a system for displaying
each multicore fiber and a fiber splicing system. According to the
invention at least one ring for surrounding each multicore fiber to be
spliced has an outside envelope that is homothetic (geometrically similar)
in shape to the outer envelope of each multicore optical fiber, with the
outer outside envelope of each ring being designed to be marked as a
function of analysis of the image of each multicore fiber as obtained by
means of the display system.
Inventors:
|
Le Noane; Georges (Tregastel, FR);
Perrin; Gabrielle (Ploubezre, FR);
Le Marer; Rene (Tregastel, FR)
|
Assignee:
|
France Telecom (FR)
|
Appl. No.:
|
674675 |
Filed:
|
July 2, 1996 |
Foreign Application Priority Data
Current U.S. Class: |
385/95; 385/71; 385/99; 385/147 |
Intern'l Class: |
G02B 006/255 |
Field of Search: |
385/95,96,97,98,99,71,147
|
References Cited
U.S. Patent Documents
5384870 | Jan., 1995 | Lieber | 385/71.
|
Foreign Patent Documents |
A-0427 705 | May., 1991 | EP.
| |
A-2 236 198 | Jan., 1975 | FR.
| |
A-2 701571 | Aug., 1994 | FR.
| |
Other References
Patent Abstract of Japan: vol. 12 No. 276, p. 737, Jul. 30, 1988 Method for
Aligning Multicore Optical Fiber.
Patent Abstract of Japan: vol. 7 No. 231, p. 229, Oct. 13, 1983 Manufacture
of Multicored Optical Connector and Its Core.
|
Primary Examiner: Palmer; Phan T. H.
Attorney, Agent or Firm: Blakely Sokoloff Taylor & Zafman
Claims
We claim:
1. Identifying and splicing apparatus for identifying and splicing at least
one multicore optical fiber, the apparatus including both a display system
for each multicore fiber and a fiber splicing system, the apparatus
further including at least one ring surrounding each multicore fiber to be
spliced and having an outside envelope that is homothetic (geometrically
similar) in shape to that of the outer envelope of each multicore optical
fiber, the outside envelope of each ring being designed to be marked as a
function of analyzing the image of each multicore fiber by means of the
display system.
2. Identifying and splicing apparatus according to claim 1, wherein each
ring includes a central opening suitable for receiving a multicore fiber,
said central opening being of shape and dimensions that correspond to the
outside shape and dimensions of the multicore fiber with a certain amount
of clearance to facilitate insertion with precentering of the multicore
fiber in the ring.
3. Identifying and splicing apparatus according to claim 2, wherein each
ring includes an inlet duct for the multicore fiber, which duct is
circularly cylindrical in shape about an insertion axis X and is extended
internally by a funnel-shaped guide duct leading to one end of the central
opening, said cylindrical inlet duct having dimensions that are greater
than those of the multicore fiber in order to facilitate insertion of the
fiber into the ring.
4. Identifying and splicing apparatus according to claim 1, wherein each
ring is square in outside shape, having four corners with cut-off flats
suitable for being marked.
5. Identifying and splicing apparatus according to claim 1, including
automatic marking equipment suitable for marking each ring as a function
of the image of each multicore fiber being analyzed by means of the
display system, to identify on each ring at least one reference core of
said multicore fiber.
6. Identifying and splicing apparatus according to claim 5, wherein the
automatic marking equipment includes a plurality of individual automatic
marking devices suitable for being positioned around said ring and for
being triggered individually as a function of the image analysis.
7. Identifying and splicing apparatus according to claim 5, wherein the
automatic marking equipment includes a single individual marking device
suitable for being mounted to rotate about a ring and to take up a
determined marking position in response to an order issued in response to
analysis of the image of the multicore fiber.
8. Identifying and splicing apparatus according to claim 1, including a
mounting support comprising a deep first V-shaped groove designed to
receive a ring and, in line therewith, a shallow second groove provided at
its end with a retractable abutment, said second groove being designed to
receive a stripped multicore fiber without special adjustment, inserted
through the ring, and brought into abutment against the retractable
abutment.
9. Identifying and splicing apparatus according to claim 8, wherein the
mounting support includes a longitudinal abutment for the ring, which
abutment is formed by the step situated at the connection between the
first groove and the second groove.
10. Identifying and splicing apparatus according to claim 8, wherein a
presser system is provided on the mounting support to press the ring into
the deep first V-shaped groove, and wherein the display system is placed
behind the retractable abutment of said mounting support, facing the end
of the second groove.
11. Identifying and splicing apparatus according to claim 1, wherein the
splicing system comprises at least one deep V-shaped groove designed to
receive two rings, each threaded over a multicore fiber to be spliced,
said rings being received end-to-end, said deep V-shaped groove including
a shallow central portion that is V-shaped and suitable for receiving the
stripped multicore fibers to be spliced after they have passed through
said rings, said fibers being received directly and without any further
manipulation, and being positioned facing one another ready for splicing.
12. Identifying and splicing apparatus according to claim 11, wherein the
splicing system includes a plurality of parallel deep V-shaped grooves for
receiving a plurality of rings each having a central portion constituted
by a shallower V-shaped groove for supporting the stripped multicore
fibers.
13. A method of identifying and splicing at least one multicore optical
fiber using identifying and splicing apparatus according to claim 1, the
method consisting in the steps consisting in:
positioning a ring in a mounting support in abutment against the step
formed at the connection between the first and second v-shaped grooves;
inserting a multicore fiber to be spliced in said ring in such a manner
that the stripped multicore fiber emerging from the ring comes into
abutment against the retractable abutment of the mounting support;
after the retractable abutment has been retracted, displaying the cleaved
front face of the multicore fiber by means of the display system;
as a function of analyzing the image obtained by means of the display
system, marking the outside surface of the ring by means of the automatic
marking device;
placing the marked ring provided with the multicore fiber to be spliced in
the splicing system in such a manner that the stripped multicore fiber
emerging from said ring is positioned in the shallow V-shaped central
groove;
positioning another multicore fiber inserted in another marked ring to face
the multicore fiber that is to be spliced; and
sticking together under ultraviolet radiation the two fiber ends that are
pressed down against the bottom of the shallow common V-shaped central
groove.
Description
The present invention relates to apparatus for and to a method of
identifying and splicing at least one multicore optical fiber.
More particularly, it relates to apparatus including both a system for
displaying each multicore fiber, and a system for splicing fibers.
A particularly advantageous application of the invention lies in splicing
multicore monomode fibers, in the factory or on site, while ensuring that
each individual waveguide is identified and accurately spliced whether
during installation or during a repair.
BACKGROUND OF THE INVENTION
Multicore fiber splicing systems are already known that make use of a
reference alignment system such as a V-shaped groove or a ferrule,
enabling the fibers which are to be spliced to be put directly into
alignment.
Splicing systems are also known that operate by melting multicore fibers.
The major drawback of such splicing systems making use of direct alignment
or of melting is that they do not guarantee easy identification of the
fiber cores to be aligned, even if it is possible during welding to
envisage displaying the cores and rotating the fibers so as to make the
cores match.
Such a drawback can severely limit the use of such multicore fibers in an
optical fiber distribution network.
Although it is acceptable during network installation to look for
waveguides that communicate from one end of a link to the other, with each
multicore fiber itself being identified by color coating like a
conventional optical fiber, and also by the respective colors of cable
assembly elements, the same does not apply when repairing cables or when
reorganizing connections, e.g. in distribution or splitting units.
It should be emphasized that during repair, it is essential to reduce the
intervention time needed to put the subscriber's link back into operation.
If a repair is performed blind, i.e. without fiber identification so as to
keep intervention time down, then it is necessary to perform new overall
identification of links that have been cut and then repaired, thus giving
rise to intervention which is difficult and lengthy, taking place both at
the exchange and at the branching points concerned.
Also, document FR 2 701 571 discloses high-accuracy multicore optical
waveguides of small size, which waveguides make use of a high-precision
matrix. Such a matrix makes it possible, in particular, to facilitate
operations of splicing such waveguides. Such multicore fibers may contain
N cores, where N lies, for example, in the range 4 to 16.
According to that document, provision is made for the waveguides to be
coated in protective coating analogous to the coating of a conventional
fiber with the exception that it is provided with identification means,
e.g. a sector of a color that is different from the remainder of the
coating.
Thus, if the identification means can be implemented merely in the form of
a mark in the coating of the fiber, it is possible to envisage
distinguishing a particular one of the cores in the multicore matrix. Such
distinction can be achieved merely by changing an opto-geometrical
characteristic of an individual waveguide, e.g. by having a core diameter
that is considerably smaller or considerably greater than the diameter of
the other N-1 cores in the waveguide.
Although the use of a core that is significantly different from the others
in a four-core fiber can compromise use thereof in high-data rate
transmission, thus reducing the potential of such a fiber, in a nine-core
fiber, for example, one of the cores can advantageously be identifiable in
this manner while simultaneously serving to connect a subscriber to a
remote surveillance function.
It should be observed that identification by marking the protective coating
of the fiber remains difficult to implement during fiber-drawing, and is
in any case difficult to make use of on site, given the small size of the
coating and the danger of confusion.
It is also known that with very simple transverse illumination of the
optical fiber using white light, it is possible to display the various
different cores of the fibers after a short length, either by transverse
observation or else by observing the cleaved and polished face of the
fiber.
When splicing is being performed on site, it is very important to provide a
splicing apparatus that is not subject to any risk of error and that
avoids any need for the operator to perform difficult checks or
manipulations that would make any identification operation fiddly,
dangerous, or uncertain.
OBJECTS AND SUMMARY OF THE INVENTION
Under such conditions, the present invention proposes novel apparatus and a
novel method for identifying and splicing that take account of the
above-specified constraints and that enable the individual cores of a
multicore fiber to be spliced accurately and reliably, while maintaining
traceability of the matrices of cores to be spliced, and while minimizing
risks and operations that are difficult for an operator to perform.
More particularly, the apparatus of the invention includes at least one
ring surrounding each multicore fiber to be spliced and having an outside
envelope that is homothetic (geometrically similar) in shape to that of
the outer envelope of each multicore optical fiber, the outside envelope
of each ring being designed to be marked as a function of analyzing the
image of each multicore fiber by means of the display system.
Thus, by means of the apparatus of the invention, the contribution of the
operator is reduced merely to the simple, conventional, and usual
operations of stripping, cleaving, and inserting the multicore optical
fiber into the ring.
All of the other operations of taking account of the identification on the
ring, of traceability, and of dimensional verification, can be made
automatic, and the splicing operation can be facilitated by manipulating
accurately identified rings with fibers of guaranteed longitudinal
alignment.
Splicing quality is itself optimized by applying multicore fibers directly
in a centering device, thereby avoiding dimensional errors that may have
accumulated on any intermediate parts, and giving rise to splicing that is
very cheap since no precision parts are required.
According to a characteristic of the identification and splicing apparatus
of the invention, each ring includes an inlet duct for the multicore
fiber, which duct is circularly cylindrical in shape about an insertion
axis X and is extended internally by a funnel-shaped guide duct leading to
one end of the central opening, said cylindrical inlet duct having
dimensions that are greater than those of the multicore fiber in order to
facilitate insertion of the fiber into the ring.
In addition, according to an advantageous characteristic, the
identification and splicing apparatus of the invention includes automatic
marking equipment suitable for marking each ring as a function of the
image of each multicore fiber being analyzed by means of the display
system, to identify on each ring at least one reference core of said
multicore fiber.
According to a particularly advantageous characteristic, the apparatus of
the invention includes a mounting support comprising a deep first V-shaped
groove. designed to receive a ring and, in line therewith, a shallow
second groove provided at its end with a retractable abutment, said second
groove being designed to receive a stripped multicore fiber without
special adjustment, inserted through the ring, and brought into abutment
against the retractable abutment.
Longitudinal alignment of the multicore fiber, and thus a guarantee that it
is properly positioned in the splicing system, is thus ensured by putting
the fiber into abutment against the retractable abutment of the mounting
support of the apparatus of the invention while the fiber is being
inserted into the ring, and by the fiber being prevented from moving
therein, e.g. by adhesive.
According to a characteristic of the apparatus of the invention, the
mounting support includes a longitudinal abutment for the ring, which
abutment is formed by the step situated at the connection between the
first groove and the second groove.
In addition, in the apparatus of the invention for identification and
splicing, the splicing system comprises at least one deep V-shaped groove
designed to receive two rings, each threaded over a multicore fiber to be
spliced, said rings being received end-to-end, said deep V-shaped groove
including a shallow central portion that is V-shaped and suitable for
receiving the stripped multicore fibers to be spliced after they have
passed through said rings, said fibers being received directly and without
any further manipulation, and being positioned facing one another ready
for splicing.
Thus, the longitudinal positioning of the fibers which requires accuracy to
within a few microns is ensured, without the drawback of performing
sensitive manipulation of the two fibers by putting the rings into
abutment, said rings having previously ensured that the fibers are
longitudinally positioned in the mounting support of the apparatus of the
invention.
With the rings in longitudinal abutment in the splicing system, in
particular in the deep grooves of the splicing system, the fibers are
automatically positioned longitudinally.
The splicing operation consists merely in applying the multicore fibers in
the central groove that is used as the centering groove.
As a result, the quality of the splice is associated essentially with the
quality of the multicore matrix and not with the accuracy of the
intermediate parts, and overall, the assembly leads to apparatus that is
extremely cheap since the N cores are spliced in a single operation that
does not require any precision parts.
The method of identifying and splicing at least one multicore optical fiber
by means of the identifying and splicing apparatus of the invention
comprises the steps consisting in:
positioning a ring in a mounting support in abutment against the step
formed at the connection between the first and second V-shaped grooves;
inserting a multicore fiber to be spliced in said ring in such a manner
that the stripped multicore fiber emerging from the ring comes into
abutment against the retractable abutment of the mounting support;
after the retractable abutment has been retracted, displaying the cleaved
front face of the multicore fiber by means of the display system;
as a function of analyzing the image obtained by means of the display
system, masking the outside surface of the ring by means of the automatic
marking device;
placing the marked ring provided with the multicore fiber to be spliced in
the splicing system in such a manner that the stripped multicore fiber
emerging from said ring is positioned in the shallow V-shaped central
groove;
positioning another multicore fiber inserted in another marked ring to face
the multicore fiber that is to be spliced; and
sticking together under ultraviolet radiation the two fiber ends that are
pressed down against the bottom of the shallow common V-shaped central
groove.
The method of the invention takes account of the various ways in which the
cores of the multicore fiber can be identified, either by marking the
covering, or, which is the most probable case, by one of the cores being
different or by the matrix being asymmetrical.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description refers to the accompanying drawings that are
given as non-limiting examples, and makes it easy to understand what the
invention consists in and how it can be implemented.
In the accompanying drawings:
FIG. 1 is a diagrammatic cross-section view of a multicore fiber having
nine cores;
FIG. 2 is a cross-section view of an identifying receiving ring forming a
portion of apparatus of the invention;
FIG. 3 is a longitudinal section view of the ring forming a portion of
apparatus of the invention;
FIG. 4 is a diagrammatic cross-section view of the FIG. 2 ring, fitted with
a multicore fiber;
FIG. 5 is a longitudinal side view of the mounting support of the apparatus
of the invention;
FIG. 6 is a cross-section view of the mounting support of apparatus of the
invention;
FIG. 7 is a longitudinal section view of the splicing system of apparatus
of the invention;
FIG. 8 is a diagrammatic perspective view of the splicing system of FIG. 7;
and
FIG. 9 is a diagrammatic perspective view of a variant embodiment of the
splicing system of the apparatus of the invention.
MORE DETAILED DESCRIPTION
In FIG. 1, there is shown a cross-section of a multicore optical fiber 1
comprising a matrix of nine individual waveguides or cores 2, with one of
the cores, referenced 3, having a diameter that is different from the
others, and in this case having a diameter that is greater.
It would naturally be possible to provide for the diameter of the core 3 to
be smaller than that of the other cores.
In such a multicore optical fiber 1, it can be assumed that the core 3 that
differs from the other cores is more particularly allocated to a system
for automatic remote surveillance of subscriber links, being capable of
showing the states of such links, of detecting possible degradation at
individual waveguide joints, or of immediately establishing which section
is faulty or interrupted.
As a result, the light propagation characteristics of such an individual
waveguide may be significantly different from those of the other
individual waveguides, while nevertheless remaining compatible with the
need for isolation between the individual waveguides.
The other eight cores may be directly allocated to subscriber links using
various techniques that are already known, e.g. full duplex, or a
dedicated link or a combination of both, depending on the expected uses
and data rates.
As can be seen in FIG. 1, the multicore fiber 1 is inscribed inside a
square 4, with the individual waveguides or cores 2 being accurately
referenced within the fiber.
In the typical case as shown, the square 4 has a side of 125 micrometers,
for example.
In a multicore fiber 1 that is inscribed in a square of 125 micrometer
side, the cores of the fiber are uniformly spaced apart at about 37
micrometers and the method whereby such a fiber is made can guarantee
accuracy of much less than 1 micron both with respect to distance between
cores and with respect to the dimensions of the square in which the fiber
is inscribed, and also with respect to centering of the core matrix within
the reference envelope 4.
Advantageously, such a configuration makes it possible to align the fiber
cores during splicing by simple alignment in a V-groove, with splicing
accuracy then being associated essentially with the accuracy with which
the matrix of cores is located within the reference envelope 4 of the
optical fiber 1.
In FIG. 1, it will be observed that the core 3 which is different from the
other cores is situated in one of the corners of the square 4.
FIG. 2 is a cross-section through a ring 5 forming a portion of apparatus
of the invention, said ring 5 being designed to receive the multicore
fiber 1 for identification thereof and for splicing to another multicore
fiber of the same type.
The outside shape of the ring 5 is a square 7 which is homothetic
(geometrically similar) to the square reference envelope 4 of the
multicore fiber 1 and which includes a square-shaped central opening 6 of
dimensions that are slightly greater than those of the outer envelope 4 of
the multicore fiber 1.
By way of example, the dimensions of the square of the central opening 6 in
the ring 5 are about (125+10) micrometers so as to enable the multicore
fiber to be properly inserted inside the ring 5 while nevertheless
performing a precentering function for the splicing operation.
As can be seen in FIG. 2, the ring 5 has flats 8 cut off in all four
corners of its outer square envelope 7 so as to facilitate the marking
operation, e.g. by inking, to identify the core 3 of the multicore fiber
1.
Advantageously, such a ring may be made by a conventional technique of
molding a plastics material that enables a regular square shape to be
obtained very cheaply that is reproducible with the desired accuracy.
As can be seen in FIG. 3, the ring 5 has an inlet duct 9 for the multicore
fiber 1 which is circularly cylindrical in shape about a longitudinal
insertion axis X. This inlet duct 9 is of a diameter that is greater than
the dimensions of the central opening 6 of the ring 5 so as to facilitate
insertion of the fiber into the ring along the axis X. This inlet duct 9
is extended internally by a guide duct in the form of a funnel 10 which
leads to one end of the central opening 6.
In addition, transverse ducts 17 and 18 are provided in the ring 5 opening
out from the outside into the cylindrical inlet duct 9 and into the
central opening 6 so as to enable adhesive to be injected into the ring to
hold the multicore fiber inserted into the central opening 6 of the ring.
As can be seen more particularly in FIG. 4, when the multicore fiber 1 is
threaded inside the ring 5, the core 3 which is different from the other
cores 2 is in a position corresponding to a corner of the outer square 7
and thus to one of the cut-off flats 8 of the ring 5. The core 3 can
therefore take up four different positions.
The mark to be made on the cut-off flat corresponding to the position of
the core 3 in the multicore fiber will be used for identification purposes
when splicing the fiber to another fiber of the same type.
As shown in FIG. 5, the ring 5 is disposed on a mounting support 12. This
mounting support 12 is provided with a deep first V-shaped groove 13 that
is designed to support the ring 5.
This deep first V-shaped groove 13 is extended longitudinally from one of
its ends by a shallow second V-shaped groove 15 suitable for receiving the
bare multicore fiber 1 inserted into the ring 5 and emerging therefrom,
and suitable for receiving it without any special adjustment.
At the end of this shallow second V-groove 15, there is provided a
retractable abutment 16.
When the stripped multicore fiber 1 is inserted through the ring 5, it
takes up a position in the shallow second groove 15 and comes into
abutment against the retractable abutment 16 positioned at an outlet
position.
The step between the deep first groove 13 and the shallow second groove 15
provides a longitudinal abutment for the ring 5.
A presser system 14 is also provided to press the ring 5 into the deep
first groove 13.
In a manner that is very simple and cheap, such a support 12 ensures that
the ring 5 and the multicore fiber 1 are properly positioned
longitudinally.
After the multicore fiber has been put into abutment within the ring, the
multicore fiber is stuck to the inside of the ring using the adhesive feed
channels 17 and 18, after which the retractable abutment is retracted so
as to make it possible to perform identification on the multicore fiber.
The display system of the apparatus of the invention serves to display the
cleaved face of the multicore fiber 1.
It comprises a camera 19 provided with an optical system that is positioned
behind the retractable abutment 16 facing the cleaved face of the
multicore fiber 1 positioned in the groove 15 of the mounting support 12.
The camera 19 is suitable for observing the front face of the fiber, and
in particular for providing an image of the matrix of cores which are
illuminated by means of a light source 20 adapted to such an application.
Such a camera display system is also known in apparatuses made for splicing
together conventional monomode optical fibers by welding.
The image of the matrix of cores in the fiber 1 maybe displayed on a screen
21 connected to the camera 19 so as to enable the operator to inspect
visually the fiber that is to be spliced.
At this point it is possible for the operator to observe on the screen 21
any major defect in the fiber, e.g. in the cleaving of the front face of
the fiber, in which case the operator may suspend the splicing operation.
If the fiber is badly cleaved, the very small cost of the ring 5 makes it
possible to eliminate said part and start splicing again from the
beginning.
The image may be analyzed by means of appropriate software serving to
provide information concerning the accuracy of the multicore matrix,
whether with respect to the outside shape of the fiber or with respect to
the disposition of the cores within the matrix.
Such information can be most advantageous for a splice of this type, either
for giving unambiguous information about the mean level of losses obtained
during splicing, or else for maintaining traceability of splices performed
in a distribution zone.
As shown in FIG. 6, an automatic marking device 22, 23, 24, and 25 is
provided on the mounting support 12 for the purpose of marking the outer
envelope 7 of each ring 5 as a function of the analysis performed on the
image of each multicore fiber using the screen 21 and a display system.
The marking device serves to identify on the ring 5 at least one reference
core 3 in the multicore fiber 1.
More particularly, in this case the marking device comprises a plurality of
automatic individual inking devices 22, 23, 24, and 25 located around each
ring 5 positioned in a deep groove 13 and facing the cut-off flats 8 of
the outer envelope 7 of the ring so as to enable them to ink the cut-off
flats of the ring 5 individually by means of an ink jet. Each automatic
inking device is triggered as a function of the analysis of the image
obtained on the screen 21.
In a variant, it is also possible to provide for a single individual marker
device that is suitable for being mounted so as to be rotatable relative
to the mounting support 12 about the ring 5, and for it to be positioned
in an appropriate marking position facing one of the cut-off corners of
the ring 5 in application of an order given in response to the analysis of
the image that is obtained of the multicore fiber as displayed on the
screen 21.
Naturally, it is possible in a variant embodiment to provide for marking by
stamping, for the date and the time of splicing to be marked, or for the
ring to be identified by any identification device other than inking.
Thus, the automatic marking device is used to mark the cut-off flat that
corresponds to the position of the core 3 of the multicore fiber.
Once the ring 5 has been marked, it is ready for use in splicing to a
corresponding multicore fiber itself positioned in another marked ring 5
of the same type.
FIGS. 7 and 8 show more particularly how two multicore fibers are spliced
together after initially being positioned in rings 5 and marked.
The splicing system of the identification and splicing apparatus of the
invention comprises a support 26 in which a deep V-shaped groove 27 is
provided for receiving the rings 5 end-to-end and provided in a central
portion with a shallow V-shaped groove 28 suitable for receiving that
stripped multicore fibers 1 that are to be spliced together where they
emerge from the rings 5.
It should be specified that the rings 5 are positioned in the groove 27
with their respective marks 34 and 35 placed at the top of the splicing
system so as to be visible after splicing.
The step between the deep V-groove 27 and the shallow central V-groove 28
serves to ensure longitudinal alignment of the rings 5 which come into
abutment against said step.
Abutment takes place at the junction 29 between the grooves of two
different depths, and as a result the stripped fibers 1 emerging from the
rings 5 naturally come into face to face relative positioning without
further handling and with a distance between the two faces that are to be
spliced together that may be of the order of a few microns, thereby
ensuring that transmission losses are very low and due solely to said
parameter of spacing between the faces.
The accuracy of such mounting is thus essentially associated with the
accuracy of the length of the central groove 28 that receives the fiber
and the accuracy with which the fibers 1 are brought into abutment in the
mounting support 12.
The centering device associated with the splicing device 26 comprises a
simple pressure-applying system that may advantageously be constituted,
for example, by a transparent plate 30 of glass or plastics material which
is pressed by a tool 31 and which enables the two ends of the fibers 1
pressed down against the bottom of the common central V-groove 28 to be
stuck together under the influence of UV radiation.
In addition, the rings 5 may be stuck by means of holes 32 formed in the
top portion 33 of the splicing support 26, or they may be snapped into
place using a well-known technique.
An operation which is always rather difficult to perform on site is thus
achieved with a minimum amount of manipulation, and in particular without
any sensitive putting into abutment of the two fibers during splicing
thereof, and the resulting splice is very cheap and highly reliable while
nevertheless, as shown in FIG. 8 which is a diagrammatic perspective of
the resulting joint, guaranteeing accurate and visible marking of the
cores of a multicore fiber, with the markings 34 and 35 always being used
on the top portions of the mounting support 26, i.e. the portion which is
visible after splicing has taken place.
FIG. 9 shows a variant of the splicing system of the identification and
splicing apparatus of the invention, in which a mounting support 36 has a
plurality of deep positioning grooves 27 disposed in parallel and each
coinciding in its central portion with a respective shallow adjustment
groove 28. Such a mounting support 36 makes it possible to splice fibers
at high density in the form of strips.
The apparatus and the method of the present invention make it simple and
cheap to transfer the intrinsic identification means in a multicore
optical fiber to an outer ring in a manner that is highly visible.
They also show the advantage of using, for the multicore fiber, a matrix
whose square shape, for example, enables the two matrices that are to be
spliced together to be centered in a device that is very cheap.
These apparatuses and methods avoid the drawback of it being difficult to
identify the individual waveguides in a multicore fiber during splicing,
whether splicing is performed in an installation or during repairs, by the
technique of transferring the identification onto the ring.
Such apparatuses and methods are cheap since none of the parts implemented
requires very great precision, whether the parts are located in the
mounting support or in the splicing system, thus making it possible to use
parts that are made of plastics material or of ceramics material or indeed
of glass, using techniques that are very cheap, such as molding.
Compared with the unit cost of splicing a monomode waveguide, the method of
the invention thus demonstrates. the enormous potential of multicore
fibers since it serves to splice together a plurality of cores, including
a core for operations of remote surveillance or of remote maintenance, in
the same amount of time as is required for splicing together a
conventional single core fiber, while guaranteeing that the individual
waveguides within the matrix are properly identified and while ensuring
that the splices performed are traceable, and without requiring precision
parts to be used.
The quality of the splicing is therefore associated essentially with the
intrinsic quality of the multicore matrix of the fiber which is a
requirement inherent to this concept based on obtaining, machining, and
assembling and drawing down high precision preforms.
The invention is not limited in any way to the embodiment described and
shown, and the person skilled in the art can make any variation that comes
within the spirit of the invention.
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